Extremely realistic. No painting required. The only tools needed are a heart-shaped cutter, a ball-ended tool and a spongy surface to work on. Pre-tint your cold porcelain in 2 colors of your choice.
This video is from the South American TV show "Bienvenidas" (Welcome). Fast forward to 11:45 for the Jorge Rubicce segment. If you don't understand the language, just mute the video and follow along visually as he demonstrates each step for creating the petals and building a rose. Jorge does a great job of clearly showing each step of the process.
Remember, fast forward to 11:45 for Rubicce segment
(when video starts, pull slider to right until 11:45 appears)
I've been asked about the ball-ended tool that Jorge is using in video. That tool is readily available in USA but is usually found with the fondant and gumpaste supplies rather than clay tools. In the past, only professional-quality tools were available for use by commercial bakers, so they were often expensive. However, because air-dry clay is becoming more and more popular in USA and making flowers is among the favorite things to do with air-dry clay, we are finally beginning to see some lower-cost flower-making tools being made available especially for clay.
Here's a few sources for some of the supplies used with this tutorial. The first two tool sets shown include a ball-ended tool. These are plastic, rather than stainless steel, which makes them inexpensive.